Environmental Assessment of Pavement Alternatives: Decision-Making in Light of Current Knowledge and Unresolved Questions John Harvey Department of Civil and Environmental Engineering University of California, Davis, USA and University of California Pavement Research Center Davis, Berkeley UCLA Lake Arrowhead Symposium October 17-19, 2010
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Environmental Assessment of Pavement Alternatives ... · Brief Overview of Life-Cycle Assessment (LCA) •A method for characterizing and quantifying ... Santero and Horvath (2009)
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Environmental Assessment of Pavement Alternatives: Decision-Making in Light of
Current Knowledge and Unresolved Questions
John HarveyDepartment of Civil and Environmental Engineering
University of California, Davis, USAand
University of California Pavement Research CenterDavis, Berkeley
UCLA Lake Arrowhead Symposium October 17-19, 2010
What is the pavement infrastructure?
• Freeways, highways
• Roads and streets
• Railroads and transit lines
• Airfields
• Land-side port facilities (container yards, loading areas)
• All have same issues regarding materials, design, management, environmental impact
• Focus today: streets and highways
Caltrans context• 24,000 centerline kilometers,
80,000 lane-kilometers
– 1/3 concrete pavement, urban high-volume freeways, 30-50 years old
– 2/3 asphalt surfaced: composite, semi-rigid, full-depth and conventional asphalt structures, original structures 20-90 years old, much maintenance and rehabilitation
• 90 % of work is maintenance,preservation, rehabilitation,recycling, reconstruction
California context• Since 1970, California’s
– population nearly doubled to 37 million
– not much increase in highway network
– estimated annual vehicle kilometers traveled quadrupled to 600 billion (400 billion vehicle miles traveled)
• Most state highway and much local work is reconstruction, rehabilitation, preservation work done at night or 24 hours/day working closures
• Need: – increased design lives (thicker
pavement) for life cycle cost
– faster construction (thinner pavement and faster materials)for traffic delay
Current situation facing decision-makers
• Funding has not been sufficient to preserve existing infrastructure– Rougher pavements,
– More costly to restore capacity when funding is available
– Materials price fluctuations
• Intense competition from two competing industries (asphalt and concrete), each currently trying to win market share by “green marketing”– A great deal of information, most of it contradictory
• Political pressure for rapid implementation of green “rating” systems– Like LEEDS for buildings
Brief Overview of Life-Cycle Assessment (LCA)
• A method for characterizing and quantifying environmental sustainability
• Applies a “cradle-to-grave” perspective when analyzing products or systems
• Measures inputs and outputs of a product or system
– Example inputs: energy, water, materials
– Example outputs: air emissions, waste
– Can be categorized into impact categories
• General standards set by ISO 14040 series
– Provides general LCA guidance, but lacks detailed information necessary for individual products and systems
Why Apply LCA to Pavement?
• Three part state strategy for transportation for GHG emission reduction
– Increase fuel economy of vehicles
– Reduce GHG content of fuel
– Reduce car and truck travel
• Can pavement be the fourth strategy?
– Rate of market penetration can potentially be faster than other strategies
• Other environmental benefits: reduce regulated pollutants and non-renewable resource use
Southern CaliforniaProjected aggregate useCircle is use to 2050Blue is permitted portionPurple is shortageTriangles are permitted quarries
W, P
W, PW, P
Generic Life cycle assessment
• Evaluates a product or system throughout its entire life cycle
Raw Material
Acquisition
Material Processing
Manufac-turing
UseEnd-of-
Life
RecycleRemanufacture
Reuse
M,E
W, PW, P
M,E M,E M,E M,E
M = MaterialsE = EnergyW = WasteP = Pollution
= Transport
Recycle
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The Pavement Life Cycle
Materials
End-of-Life
Maintenance &
Rehabilitation
Use
Construction
Materials extraction and production
Transportation
Onsiteequipment
- Carbonation- Lighting- Albedo (?)- Rolling resistance- Leachate
Traffic delay
Existing Pavement LCA Studies• Roughly 15 studies since 1995
– Attempt to quantify the environmental impact of all pavements using a very limited example set
– Most aim at comparing asphalt versus concrete
– Differing scopes
• Region of study
• Design and design life
• System boundary
• Environmental impacts
– Different assessment criteria
– Very difficult/impossible to compare results of one study to another due to fundamental differences in scope
What is being done to improve Pavement LCA?
• Workshop held May, 2010 at UCD– Invited international attendees from pavement and